On Mon, Jan 9, 2017 at 10:08 AM, Bala Manoharan <bala.manoha...@linaro.org> wrote: > Except for the Minor documentation comment below > > Reviewed-by: Balasubramanian Manoharan <bala.manoha...@linaro.org> > > On 5 January 2017 at 20:25, Bill Fischofer <bill.fischo...@linaro.org> wrote: >> Introduce three new APIs that support efficient sharing of portions of >> packets. >> >> odp_packet_ref_static() creates an alias for a base packet >> >> odp_packet_ref() creates a reference to a base packet >> >> odp_packet_ref_pkt() creates a reference to a base packet from a supplied >> header packet >> >> In addition, two other APIs simplify working with references >> >> odp_packet_is_ref() says whether a packet is a reference >> >> odp_packet_unshared_len() gives the sum of data lengths over all unshared >> packet segments. These are the only bytes of the packet that may be >> modified safely. >> >> Signed-off-by: Bill Fischofer <bill.fischo...@linaro.org> >> --- >> Changes in v6: >> - Miscellaneous formatting corrections >> - Minor documentation improvements >> >> Changes in v5: >> - Clarified that both input packets to odp_packet_ref_pkt() must be from the >> same pool and results are undefined if they are not. >> - Clarified that input(s) to reference create APIs may be references and that >> implementations are free to perform partial or full packet copies if needed >> to support such compound references. >> - Removed odp_packet_has_ref() and redefined odp_packet_is_ref() to indicate >> simply whether other handles exist that share bytes with this packet. >> - Modified validation tests to reflect the above changes. >> >> Changes in v4: >> - Bug fixes >> - Expand validation testing to cover extensions on packets with references >> >> Changes in v3: >> - Rebased to latest API-NEXT >> - Bug fixes >> - Eliminate concept of base packets, both references and referenced packets >> may >> have head extensions as needed >> include/odp/api/spec/packet.h | 172 >> +++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 171 insertions(+), 1 deletion(-) >> >> diff --git a/include/odp/api/spec/packet.h b/include/odp/api/spec/packet.h >> index 4a86eba..9b6681c 100644 >> --- a/include/odp/api/spec/packet.h >> +++ b/include/odp/api/spec/packet.h >> @@ -256,6 +256,20 @@ uint32_t odp_packet_seg_len(odp_packet_t pkt); >> uint32_t odp_packet_len(odp_packet_t pkt); >> >> /** >> + * Packet unshared data len >> + * >> + * Returns the sum of data lengths over all unshared packet segments. These >> + * are the only bytes that should be modified by the caller. The rest of the >> + * packet should be treated as read only. odp_packet_unshared_len() will be >> + * equal to odp_packet_len() if odp_packet_is_ref() is 0. >> + * >> + * @param pkt Packet handle >> + * >> + * @return Packet unshared data length >> + */ >> +uint32_t odp_packet_unshared_len(odp_packet_t pkt); >> + >> +/** >> * Packet headroom length >> * >> * Returns the current packet level headroom length. >> @@ -795,7 +809,7 @@ uint32_t odp_packet_seg_data_len(odp_packet_t pkt, >> odp_packet_seg_t seg); >> * data pointers. Otherwise, all old pointers remain valid. >> * >> * The resulting packet is always allocated from the same pool as >> - * the destination packet. The source packet may have been allocate from >> + * the destination packet. The source packet may have been allocated from >> * any pool. >> * >> * On failure, both handles remain valid and packets are not modified. >> @@ -848,6 +862,162 @@ int odp_packet_split(odp_packet_t *pkt, uint32_t len, >> odp_packet_t *tail); >> >> /* >> * >> + * References >> + * ******************************************************** >> + * >> + */ >> + >> +/** >> + * Create a static reference to a packet >> + * >> + * A static reference is used to obtain an additional handle for referring >> to >> + * a packet so that the storage behind it is not freed until all references >> to >> + * the packet are freed. This can be used, for example, to support efficient >> + * retransmission processing. >> + * >> + * The intent of a static reference is that both the packet and the returned >> + * reference to it will be treated as read only after this call. Results are >> + * undefined if this restriction is not observed. >> + * >> + * Static references have restrictions but may have performance advantages >> on >> + * some platforms if the caller does not intend to modify the reference >> + * packet. If modification is needed (e.g., to prefix a unique header onto >> the >> + * packet) then odp_packet_ref() or odp_packet_ref_pkt() should be used. >> + * >> + * @param pkt Handle of the packet for which a static reference is >> + * to be created. >> + * >> + * @return Handle of the static reference packet >> + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. >> + */ >> +odp_packet_t odp_packet_ref_static(odp_packet_t pkt); >> + >> +/** >> + * Create a reference to a packet >> + * >> + * Create a dynamic reference to a packet starting at a specified byte >> + * offset. This reference may be used as an argument to header manipulation >> + * APIs to prefix a unique header onto the shared payload. The storage >> + * associated with the referenced packet is not freed until all references >> to >> + * it are freed, which permits easy multicasting or retransmission >> processing >> + * to be performed. Following a successful call, the shared portions of the >> + * referenced packet packet should be treated as read only. Results are >> + * undefined if this restriction is not observed. >> + * >> + * This operation logically prepends a zero-length header onto the >> referenced >> + * packet beginning at the specified offset. This header is always drawn >> from >> + * the same pool as the referenced packet. >> + * >> + * Because references are unique packets, any bytes pushed onto the head of >> a >> + * reference via odp_packet_push_head() or odp_packet_extend_head() are >> unique >> + * to this reference and are not seen by the referenced packet or by any >> other >> + * reference to the same packet. Similarly, any bytes pushed onto the >> + * head of the referenced packet are not visible to any reference created >> + * prior to the push operation. >> + * >> + * Note that the existence of references does not in any way change the >> + * requirement that a single packet handle may only be manipulated by one >> + * thread at a time. The odp_packet_unshared_len() API may be used to >> + * determine the number of bytes starting at offset zero that are unique to >> + * this packet handle. Only these bytes should be considered modifiable. All >> + * other bytes accessible from this handle should be treated as read only. >> + * >> + * The packet used as input to this routine may itself by a reference to >> some >> + * other packet. Implementations that are unable to support such compound >> + * references without copies MAY perform a partial or full packet copy >> + * operation to return a valid reference in response to this call. >> + * >> + * If the caller does not indend to push a header onto either the returned >> + * reference or the packet being referenced, or otherwise modify either >> + * packet, the odp_packet_ref_static() API may be used. This may be a more >> + * efficient means of obtaining another reference to a packet if both will >> be >> + * treated as read only. >> + * >> + * @param pkt Handle of the packet for which a reference is to be >> + * created. >> + * >> + * @param offset Byte offset in pkt at which the shared reference is to >> + * begin. This must be in the range 0..odp_packet_len(pkt)-1. >> + * >> + * @return Handle of the reference packet >> + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. >> + */ >> +odp_packet_t odp_packet_ref(odp_packet_t pkt, uint32_t offset); >> + >> +/** >> + * Create a reference to another packet from a header packet >> + * >> + * Create a dynamic reference to a packet starting at a specified byte >> offset >> + * by prepending a supplied header packet. The resulting reference consists >> of >> + * the unshared header followed by the shared referenced packet starting at >> + * the specified offset. This shared portion should be regarded as read >> + * only. The storage associated with the shared portion of the reference is >> + * not freed until all references to it are freed, which permits easy >> + * multicasting or retransmission processing to be performed. >> + * >> + * Because references are unique packets, any bytes pushed onto the head of >> a >> + * reference via odp_packet_push_head() or odp_packet_extend_head() are >> unique >> + * to this reference and are not seen by the referenced packet or by any >> other >> + * reference to the same packet. Similarly, any bytes pushed onto the >> + * head of the referenced packet are not visible to any reference created >> + * prior to the push operation. >> + * >> + * Note that the existence of references does not in any way change the >> + * requirement that a single packet handle may only be manipulated by one >> + * thread at a time. The odp_packet_unshared_len() API may be used to >> + * determine the number of bytes starting at offset zero that are unique to >> + * this packet handle. Only these bytes should be considered modifiable. All >> + * other bytes accessible from this handle should be treated as read only. >> + * >> + * Either packet used as input to this routine may itself by a reference to >> + * some other packet. Implementations that are unable to support such >> compound >> + * references without copies MAY perform a partial or full packet copy >> + * operation to return a valid reference in response to this call. >> + * >> + * The packets used as input to this routine should be drawn from the same >> + * pool. Results are undefined if this restriction is not observed. >> + * >> + * odp_packet_pool() on the returned reference returns the pool id of the >> + * header packet. >> + * >> + * @param pkt Handle of the packet for which a reference is to be >> + * created. >> + * >> + * @param offset Byte offset in pkt at which the shared reference is to >> + * begin. Must be in the range 0..odp_packet_len(pkt)-1. >> + * >> + * @param hdr Handle of the header packet to be prefixed onto pkt to >> create >> + * the reference. If this is specified as ODP_PACKET_INVALID, >> + * this call is equivalent to odp_packet_ref(). The supplied >> hdr >> + * must be distinct from pkt and results are undefined if an >> + * attempt is made to create circular references. > > We can add documentation that if 'hdr' or 'pkt' is ODP_PACKET_INVALID > then then api will fail.
The intent here is that hdr can be specified as ODP_PACKET_INVALID, in which case this call is equivalent to odp_packet_ref(). I believe this was Petri's suggestion, but I have no problem with removing that feature and requiring that both pkt and hdr be valid packet handles. > >> + * >> + * @return Handle of the reference packet. This may or may not be the >> + * same as the input hdr packet. The caller should only use >> this >> + * handle since the original hdr packet no longer has any >> + * independent existence. >> + * >> + * @retval ODP_PACKET_INVALID Operation failed. Both pkt and hdr are >> unchanged. >> + */ >> +odp_packet_t odp_packet_ref_pkt(odp_packet_t pkt, uint32_t offset, >> + odp_packet_t hdr); >> + >> +/** >> + * Test if a packet is a reference >> + * >> + * A packet is a reference if any other packet handles exist that share any >> + * data bytes with this packet. >> + * >> + * @param pkt Packet handle >> + * >> + * @retval 0 Packet is not a reference. All bytes in this packet are >> unshared. >> + * @retval 1 Packet is a reference. One or more other packet handles exist >> + * that share bytes with this packet. >> + */ >> +int odp_packet_is_ref(odp_packet_t pkt); >> + >> +/* >> + * >> * Copy >> * ******************************************************** >> * >> -- >> 2.7.4 >>
